 
#define RCC_APB2ENR (*(unsigned int *)0x40021018)	

#define GPIOA_CRL (*(unsigned int *)0x40010800)

#define GPIOA_ODR (*(unsigned int *)0x4001080C)
void SystemInit(void);
void Delay_ms(volatile  unsigned  int);
void Delay_ms( volatile  unsigned  int  t)
{
     unsigned  int  i;
     while(t--)
         for (i=0;i<800;i++);
}
int main(){
	   RCC_APB2ENR |=(1<<2);// ?? GPIOA ??,(1<<2)???,?1????,????RCC???
	   GPIOA_CRL &=0xfffff000;//????????
	   GPIOA_CRL |=0x00000111;
	
	   
	  GPIOA_ODR |=0xffffffff;//??????
	 while(1)
	 {  
		 GPIOA_ODR &=0xfffffffe;//?A0??0,??LED
      Delay_ms(100000000);       //????
		 GPIOA_ODR |=0xffffffff;//?????????????,??
		 Delay_ms(10000000);
		 
		 GPIOA_ODR &=0xfffffffd;//A1?
		   Delay_ms(10000000);
		   GPIOA_ODR |=0xffffffff;
		 Delay_ms(10000000);
		 
		  GPIOA_ODR &=0xfffffffb;//A2?
		  Delay_ms(10000000);
		 GPIOA_ODR |=0xffffffff;
		 Delay_ms(10000000);
	 }
 
}
 
 
void SystemInit(){
	
}